Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02909883 2016-06-15
DISCONNECTABLE PRESSURE-PRESERVING ELECTRICAL CONNECTOR AND
METHOD OF INSTALLATION
Field of Invention
The present invention relates to an electrical connector for use in a well;
and,
more specifically, to a dis-connectable dielectric grease-packed plug that
purposefully
preserves pressure within a well bore upon separation of an electrical
conductor bundle
from a wellhead hanger connection.
Background of Invention
Occasionally, but fortunately not often, the production tubing on an oil and
gas
well will fail or "part" (i.e., separate), due to corrosion problems or other
severe well
conditions. Most often, the tubing will separate at a threaded connection,
like a
coupling, or at the wellhead tubing hanger, then fall down the well bore. On a
well that
includes an electrical submersible pump, or down-hole heater, a power cable is
fixed to
this production tubing, and attached to a wellhead penetrator, or is used on a
"feed-
thru" type design. If the production tubing parts or separates, it will drop
downward,
pulling the power cable with it. This puts a severe strain on the fixed
electrical
penetrators at the surface wellhead, and often negates their sealing
capabilities. High-
pressure well fluids can then escape from the wellhead into the atmosphere.
Currently,
a wellhead penetrator that can maintain a reliable and expected seal upon a
separation
of a tubing connection, or is purpose-built to handle this catastrophic
failure, does not
exist. However, Applicants have developed a dis-connectable wellhead hanger
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connection which, if downward force is applied to the connection, allows a
"clean"
separation, leaving a reliable seal in the tubing hanger and preventing well
fluids from
escaping into the atmosphere. Typically, prior connections were made with
cleaned
pins inserted in a dry female plug. A new pin structure and method of
installation is
described covering the male pin with a dielectric grease facilitating the
connection
process and eliminating all air pockets around the pin thereby insuring a
connection
unlikely to blow apart upon significant changes of pressure within the
wellhead under
operation.
Summary of Invention
This well bore connector comprises a wellhead hanger adapted to seat in a well
head; an electrical connector mandrel inserted in the wellhead hanger; a
female pin
connection socket inserted in the electrical connector mandrel; a mini-mandrel
or feed
through assembly inserted in the wellhead hanger having one or more electrical
conductors sealed within the mandrel and extending from the mandrel; a male
pin
attached to a stripped end of an electrical conductor extending from the mini-
mandrel
or feed through assembly inserted into the female pin socket; a dis-
connectable
connection between the female pin socket and male pin within the wellhead
hanger,
permitting separation of the mini-mandrel or feed through assemblyfrom the
electrical
connector mandrel, sealing the well bore to prevent fluids from release upon
disconnection.
The well bore connector provides a shoulder within the wellhead hanger to seat
the electrical connector mandrel and provides 0-rings to seal the electrical
connector
mandrel in the wellhead hanger to inhibit migration of fluids up the wellhead
hanger.
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The electrical connector mandrel of the well bore connector is fabricated from
polyether ether ketone (PEEK) and provides a shoulder to seat the female pin
socket
within the mandrel and a snap ring to retain the female pin socket within the
mandrel.
Additionally, the exterior of the female pin socket provides 0-rings to seal
against
migration of fluids up the interior of the electrical connector mandrel and
the interior of
the female pin socket provides contact bands to establish a low resistance
electrical
connection with the male pin.
Moreover, the well bore connector described herein seals the exterior of the
mini-mandrel or feed through assembly with 0-rings against migration of fluids
up the
interior of the electrical connector mandrel and the wellhead hanger. The
interior of the
mini-mandrel or feed through assembly is preferably filed with epoxy around
each of
the one or more electrical conductors.
The well bore connector can also provide the electrical connector mandrel a
stainless steel collar between the wellhead hanger shoulder and the shoulder
on the
electrical connector mandrel which inhibits excessive deformation of the
electrical
connector mandrel in hot, high temperature wells.
Additional features that can be provided by this device include: threads for
connection of a wellhead sub assembly to the electrical connector mandrel or
an
annular space permitting the packing of the wellhead hanger with a dielectric
grease on
the surface side of the wellhead hanger to inhibit the ingress of water or
other
contaminants into the electrical connector mandrel.
The well bore connector can also provide the electrical connector mandrel with
threads for connection of a wellhead sub assembly to the electrical connector
mandrel
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and a wellhead hanger which provides threads for connection of the
wellhead sub assembly to the wellhead hanger.
The exterior surface of the male pin of the well bore connector
provides a longitudinal slot or groove permitting excess dielectric grease
covering the male pin, prior to insertion with the female pin socket, to be
extruded.
Embodiments of the applicant's invention also provide a well bore
connector assembly connected in a wellhead hanger comprising an
electrical connector mandrel inserted in the well-bore connector assembly;
a female pin connection socket inserted in the electrical connector mandrel;
a mini-mandrel or feed through assembly inserted in the well-bore
connector assembly having one or more electrical conductors sealed within
the mandrel and extending from the mandrel; a male pin attached to a
stripped end of an electrical conductor extending from the mini-mandrel or
feed through assembly inserted into the female pin socket; a dis-
connectable connection between the female pin socket and male pin, within
the well-bore connector assembly permitting separation between the
electrical connector mandrel from the mini-mandrel, sealing the well bore
and the well-bore connector assembly to prevent fluids from release upon
disconnection. This unitary device could be assembled off-site and installed
with a compatible wellhead hanger without undue delay. Each of the
features of this device replicate the features of the well bore connector
previously described herein.
Other embodiments of the invention also provide a method for
installing a dis-connectable electrical connection for use in a wellhead
hanger which can comprise the steps of connecting a female pin connector
socket to a stripped end of a upper pig tail conductor; inserting the female
pin connector socket into an electrical connector mandrel until an upper end
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of the female pin socket seats against an internal shoulder within the
electrical connector mandrel; connecting a male pin connector socket to a
stripped end of a lower electrical conductor; and, inserting the male pin
connector through a snap ring for insertion in the electrical conductor
mandrel
until the male pin engages a plurality of contact bands within the female
socket end and the snap ring engages in a channel formed within an interior
surface of the electrical connector mandrel.
The method of assembly can further comprise the step of covering the
male pin with dielectric grease before insertion in the female pin socket to
prevent ingress of fluids into the pin connection and inserting the completed
assembly into a wellhead hanger. Assembly of the well bore connector
assembly is readily accomplished. The assembly would be completed and
taken to the wellhead having an appropriate wellhead hanger and inserted in
the wellhead hanger and screwed into place by the technician retaining the
complete assembly in the wellhead.
Accordingly, in one aspect, the present invention resides in a well bore
connector comprising: a wellhead hanger adapted to seat in a well head; an
electrical
connector mandrel inserted in the wellhead hanger; a female pin connection
socket
inserted in the electrical connector mandrel; a mini-mandrel inserted in the
wellhead
hanger having one or more electrical conductors sealed within the mini-mandrel
and
extending from the mini-mandrel; a male pin attached to a stripped end of an
electrical
conductor extending from the mini-mandrel inserted into the female pin socket;
a dis-
connectable connection between the female pin socket and the male socket pin,
within
the wellhead hanger, permitting separation between the electrical connector
mandrel
from the mini-mandrel, retaining a seal of the well bore preventing fluids
from release
upon disconnection.
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In another aspect, the present invention resides in a well bore connector
assembly configured for connection in a wellhead hanger comprising: an
electrical
connector mandrel inserted in the well-bore connector assembly; a female pin
connection socket inserted in the electrical connector mandrel; a mini-mandrel
inserted
in the well-bore connector assembly having one or more electrical conductors
sealed
within the electrical connector mandrel and extending from the mini-mandrel; a
male
pin attached to a stripped end of an electrical conductor extending from the
mini-
mandrel inserted into the female pin socket; a dis-connectable connection
between the
female pin socket and male pin, within the well-bore connector assembly
permitting
separation between the electrical connector mandrel from the mini-mandrel,
sealing the
well bore and the well-bore connector assembly to prevent fluids from release
upon
disconnection.
In a further aspect, the present invention resides in a method for installing
a dis-connectable electrical connection for use in a wellhead hanger
comprising the
steps of: connecting a female pin connector socket to a stripped end of a
upper pig tail
conductor; inserting the female pin connector socket into an electrical
connector
mandrel until an upper end of the female pin socket seats against an internal
shoulder
within the electrical connector mandrel; connecting a male pin connector
socket to a
stripped end of a lower electrical conductor; and, inserting the male pin
connector
through a snap ring for insertion in the electrical conductor mandrel until
the male pin
engages a plurality of contact bands within the female socket end and the snap
ring
engages in a channel formed within an interior surface of the electrical
connector
mandrel.
In another aspect of the invention, there is provided a wellhead connector
including: a wellhead hanger adapted to seat in a well head; an electrical
connector
mandrel inserted in the wellhead hanger; a female pin connection socket
inserted in the
electrical connector mandrel; a mini-mandrel inserted in the wellhead hanger
having
one or more electrical conductors sealed within the mini-mandrel and extending
from
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the mini-mandrel; a male pin attached to a stripped end of an electrical
conductor
extending from the mini-mandrel inserted into the female pin socket; a
connection
between the female pin socket and the male socket pin, within the wellhead
hanger,
adapted to permit separation of the electrical connector mandrel from the mini-
mandrel
upon the production tubing parting from the wellhead hanger, while retaining a
seal of
the well bore without disconnecting the electrical connector mandrel and
preventing
fluids from release upon disconnection.
In yet another aspect of the invention, there is provided a wellhead connector
assembly configured for connection in a wellhead hanger including: an
electrical
connector mandrel inserted in the wellhead hanger; a female pin connection
socket
inserted in the electrical connector mandrel; a mini-mandrel inserted in the
wellhead
hanger and having one or more electrical conductors sealed within the
electrical
connector mandrel and extending from the mini-mandrel; a male pin attached to
a
stripped end of one of the one or more electrical conductors extending from
the mini-
mandrel, the male pin being inserted into the female pin socket; connection
between
the female pin socket and male pin, within the wellhead hanger, the connection
configured to permit separation of the electrical connector mandrel from the
mini-
mandrel caused by parting of a production tubing attached to the wellhead
hanger,
wherein the wellhead connector assembly continues to seal the wellbore after
disconnection of the female pin connector and the male pin to prevent fluids
from
release upon disconnection, wherein the connection is adapted to permit
separation
between the electrical connector mandrel and the mini-mandrel caused by
parting of a
production tubing coupled to the wellhead hanger, and to retain a seal of the
wellbore
without disconnecting the electrical connector mandrel and preventing fluids
from
releasing upon disconnection.
In a further aspect of the invention, there is provided a method for
installing an
electrical connection in a wellhead hanger including the steps of: connecting
a female
pin connector socket to a stripped end of an upper pig tail conductor;
inserting the
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female pin connector socket into an electrical connector mandrel until an
upper end of
the female pin socket seats against an internal shoulder within the electrical
connector
mandrel; connecting a male pin connector socket to a stripped end of a lower
electrical
conductor; and, inserting the male pin connector through a snap ring for
insertion in the
electrical conductor mandrel until the male pin engages a plurality of contact
bands
within the female socket and the snap ring engages in a channel formed within
an
interior surface of the electrical connector mandrel.
In one more preferred aspect of the invention, the male pin connector is
configured to slide out of engagement with the female pin connector in
response to a
vertical load applied by a production tubing coupled to the wellhead hanger
parting.
In another preferred aspect of the invention, the male pin connector is
configured
to slide vertically out of engagement with the female pin socket, while
retaining the
seal of the wellbore by the wellhead connector assembly, and without damaging
the
female pin socket or the electrical connector mandrel.
Brief Description of the Drawings
Fig. 1 is a cross-sectional side view of the dis-connectable pressure-
preserving electrical connector threaded into a wellhead.
Fig. IA is an end view of the three conductors in the seal sub showing the
spatial distribution of each in the dis-connectable pressure-preserving
electrical connector of the present invention.
Fig. 18 is an exploded view of the various elements of the wellhead
hanger and electrical connector mandrel disconnected from the mini-mandrel or
feed through assembly of the upper connection and from the electrical cable
set.
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Fig. 2 is cross-sectional side view of an alternative embodiment of the dis-
connectable pressure-preserving electrical connector seated on a steel collar
and
threadable into a seal sub assembly located on the wellhead external surface.
Fig. 2A is an exploded side view of the elements of the embodiment shown in
Fig.
2.
Fig. 3 is a cross-sectional side view of the invention showing the connection
to
the seal sub assembly inserted into a groove in the wellhead hanger and
showing an
annular void at the wellhead groove for insertion of packing material.
Fig. 3a is an exploded side cross-sectional view of each of the parts of the
, 10 embodiment shown in Fig. 3.
Fig. 4 is another embodiment of the dis-connectable pressure-preserving
electrical connector threadably engaging a seal sub assembly inserted in the
top of a
wellhead hanger.
Fig. 4A is an exploded side cross-sectional view of the embodiment described
in
Fig. 4.
Fig. 5 describes the components of the dis-connectable pressure-preserving
electrical connector showing the point of separation of the mini-mandrel or
feed
through assembly from the electrical connector mandrel which remains sealed
within
the wellhead hanger.
Fig. 6 is a detailed drawing of the female pin socket connected to the
stripped
end of the first electrical conductor entering from the surface and the male
pin
connector having a longitudinal slot or groove, which is attached with set
screws to the
stripped end of the second electrical conductor extending into the well bore.
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Fig. 7 is a cross-sectional side view of another embodiment showing a mandrel
seated within a wellhead hanger and connected to an internal electrical
connector
mandrel having a canned pump coupler which permits a dis-connectable pressure-
preserving seal if the production tubing and the attached electrical cable
connector part
from the wellhead hanger.
Fig. 8 is an exploded view of the embodiment described in Fig. 7 above.
Detailed Description of the Invention
Fig. 1 shows an embodiment of this invention providing an electrical connector
mandrel 103 installed into a wellhead hanger 101. The electrical connector
mandrel
103 seated on interior wellhead shoulder 104 and is sealed within the wellhead
hanger
101 with 0-rings 123 thereby preventing fluid under pressure from leaking out
of the
well bore. Surface power cable leads or pigtails 111 are inserted into the
interior of the
wellhead hanger 101, then into the electrical connector mandrel 103. While
only one
electrical cable is shown in Fig. 1 on the interior of the electrical
connector mandrel
103, there are three such conductors for the three-phase electrical power
required by
all modern ESPs. The relative position of each of these conductors is more
fully shown
in Fig. la that shows a cross-sectional view of the three conductors 111 in
electrical
connector mandrel 103 seated within the wellhead hanger body 101.
Upon installation of this assembly, a female pin connection socket 113 of Fig.
1 is
inserted into the electrical connector mandrel 103 seating on shoulder 114 and
provides 0-rings 115 around its exterior distal end to seal against the
interior of the
electrical connector mandrel 103. The stripped end 119 of the electrical
cables 121
from the ESP are inserted into the male pin connector sleeve 118 from below,
and
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affixed therein by set screws 118' in this embodiment, and can compressively
engage
on contact bands 116 on the interior of the female connector sleeve or pin
connection
socket 113. The electrical cable is stripped to a distance at 120 to seat the
pin
connection sleeve 118. The pin connection sleeve 118 could alternatively be
attached to
.. the electrical cable 121 by crimping over the stripped end of the
electrical cable 119.
The female pin connection socket 113 is retained within the electrical
connector
mandrel 103 by snap ring 117, which is inserted upon installation into a
circular
groove 130 formed on the interior of the electrical connector mandrel 103. The
mini-
mandrel or feed through assembly 105 is filled with epoxy 126 thereby sealing
the
upper portion of the feed through assembly 105. If the electrical conductors
or their
shielded cable are separated from the wellhead hanger 101, this female pin
connection
socket 113 would allow the cabling to separate and freely disconnect and drop
away
from the wellhead hanger 101 without opening the wellhead hanger 101 to the
internal
well pressure. Since the connector is confined within the electrical connector
mandrel
103, there is no chance of escape of well fluids under potential high
pressure.
Fig. lb is an exploded view of the embodiment described above. The wellhead
hanger body 101 provides a distinct shoulder 104 permitting the electrical
connector
mandrel 103 to be inserted until it seats against the shoulder 104. The female
pin
socket 113 is attached to the stripped end of the surface cable 111' in a
manner not
shown herein but could be by crimping, set screws, welding or the like because
these
pig tails can be assembled off site. A slot or groove 131 allows a dielectric
silicone
grease, such as Dow Corning DC 111, to be installed over the male pin 118
prior to
insertion in the female pin connection socket 113. Wear or contact bands 116
are more
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clearly depicted in this view and allow the male pin 118 to seat in the female
pin
connection socket 113. This connection is made with little or no electrical
resistance
despite having a thick layer of dielectric grease smeared over the male pin
118 prior to
insertion in the female pin socket 113. All of the other features shown in
Fig. lb are
identical to those shown and described in Fig. 1.
Fig. 2 is a modified embodiment of the present invention showing an electrical
connector mandrel 203 compressively seated in a wellhead hanger recess 202.
Each
electrical conductor can also inserted in an elastomeric seal (not shown) on
an interior
surface of a seal sub (not shown), all in a manner well known in this art.
All of the described embodiments, shown in Figs. 1-5 and 7 provide similar
elements and are installed in a similar manner. For example, Fig. 2a is an
exploded view
of the structure shown in Fig. 2 showing the stainless steel collar 204,
creating an
interior shoulder 205 provided to prevent extrusion of the PEEK internal
electrical
mandrel 203 in high temperature, high pressure well situations; the threading
206 on
the exterior end of the electrical mandrel 203 for connection to a well head
device such
as a seal sub (not shown in this view), and more clearly shows the wear bands
116 on
the interior of the female pin socket 113.
Similarly, Fig. 3A is an exploded view of the structure shown in Fig. 3 that
shows
the seal sub 307 connected to the threaded end of the internal electrical
mandrel 203
and seated within the groove on the wellhead hanger 201. The upper portion of
each
electrical conductor 121 extending from the ESP cable through the mini-mandrel
or
feed through assembly 105 to the surface is stripped at its proximal end 119
for
insertion in a male pin connector sleeve assembly 118 which is inserted into
the female
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pin socket 113, and the entire assembly is moved into the internal electrical
connector
mandrel 103, 203, while the stripped end of an exterior cable having a male
socket pin
118, attached on the stripped end 119 of the conductor 121, is moved into the
electrical connector mandrel 103, 203, to seat within the female pin socket
113. Both
the male connector pin socket 118 and the female pin connector socket 113 are
attached, such as by crimping the exposed end of the conductor on the interior
of each
respective pin socket. The preferred method for connection of both the male
and female
socket is by set screws.
Finally, Fig. 4a shows an exploded view of the structure of Fig. 4 showing the
seal
sub 407 threaded both internally and externally for seating the sub in the
wellhead
hanger with threads 409 and the internal threads connecting to the threaded
end of the
internal electrical mandrel 206.
Dielectric grease, such as Dow Corning Corporation's DC 111, coats the
exterior
of the insulation of the electric conductor cable 118, to prevent ingress of
fluids which
might short the electrical connection between the male and female sockets. The
same
dielectric grease can be used to coat the upper electrical conductor set 111,
111' as they
enter the exterior of the wellhead hanger through the seal subs 307, 407 in
Figs. 3-4,
thereby preventing water or contaminants from reaching the socket connection
on the
interior of the electrical connector mandrel.
Upon separation of the production tubing from below the wellhead hanger, the
mini-mandre,1 or feed through assembly 105, in each figure would drop away
from the
electrical connector mandrel 103, 203 as shown more specifically in Figs. 1-5
and 7
removing the electrical cable 119 in its insulation 121 and disconnecting the
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connection sleeve 118, from the female pin socket 113, that remains sealed
within the
wellhead hanger 101 thereby preventing the egress of high pressure fluids up
the
interior of the wellhead hanger 101, 201, 401, 601.
Each of the embodiments shown herein is structurally similar. Only changes in
the wellhead hanger are made to accommodate the needs of the particular
application
of this invention. For example, Fig. 1 describes the electrical connector
mandrel 103
inserted in the wellhead hanger 101 as seated on a shoulder 104 on said
wellhead
hanger 101. This design is modified in Figs. 2, 3 and 4 to provide a stainless
steel collar
204 which provides a broader shoulder 205 to inhibit extrusion of the PEEK
material
from which the electrical connector mandrel 203 is formed when experience
excessive
pressure from the well bore (not shown). Fig. 2, 3 and 4 also disclose a space
213, 313
formed between the exterior of the electrical connector mandrel 203 and the
interior
surface of the wellhead hanger 201.
Fig. 5 describes the remaining seal left in the wellhead retaining the PEEK
mandrel 203 after separation of the mini-mandrel or feed through assembly 105
from
the wellhead.
Fig. 6 is a closer cross-sectional view of the male pin assembly 118 which
provides a longitudinal groove or slot 131 permitting an excess of a
dielectric grease
such as DC 111 to be extruded from the female socket 113 attached to the
stripped end
111' of electrical conductor 111. Male pin 118 is connected to stripped
electrical
conductor 119 by set screws 118', but could be attached by other means such as
crimping or the like.
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Similarly, another embodiment can allow connection of the disconnectable
assembly to a canned pump coupling as shown in Fig. 7, which functions in the
same
manner as the previously discussed embodiments. The feed-through assembly 105
is
inserted into a dummy wellhead mandrel 703 threaded into the wellhead from
above
and connecting with threads 707. The dummy mandrel seals in the wellhead with
0-
rings 705. The canned pump coupler 730 is connected to the conductors emerging
from
the PEEK mandrel assembly 103 providing a threaded upper end 736 for
attachment to
the retaining sleeve 738. Dielectric grease 734 is inserted between the top of
the PEEK
mandrel 103 and the bottom of a trash seal 732 through which each of the three
conductors are guided into the canned pump coupler 730. In all other respects,
this
embodiment functions in the same manner as the previous embodiments. The PEEK
mandrel 103 seats against the internal shoulder 715 retaining the pressure
seal at the
wellhead even if the conductors separate and fall back into the well.
Fig. 8 is an exploded view of the embodiment described in Fig. 7. Wellhead 701
is
constructed with a feed through assembly 105 which, along with the PEEK
mandrel
103, is inserted into the dummy mandrel 703 and then screwed into the interior
threads of the wellhead 707a. Retaining sleeve 738 contains the trash seal 732
and is
filled with dielectric grease to prevent the entry of water or dirt into the
top of the
wellhead pressure preserving penetrator of the present invention. The canned
pump
coupler 730 is connected to the retaining sleeve 738
Each of the alternative disclosed herein derive from a common structure and
are
variations of the disclosure made herein. Other alternatives can be fashioned
from a
similar disclosure without departing from the scope of this invention.
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The accompanying drawings and description referred to herein are illustrative
of
the invention but not restrictive thereof and together with the description
serve only to
explain the principles of the invention claimed herein.
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